diff --git a/ext/pty/extconf.rb b/ext/pty/extconf.rb
index 1b0958b484a367..da3655cf4d7118 100644
--- a/ext/pty/extconf.rb
+++ b/ext/pty/extconf.rb
@@ -17,7 +17,7 @@
   if openpt
     have_func("ptsname_r") or have_func("ptsname")
   end
-  if openpt
+  if openpt or
       (util or have_func("openpty")) or
       have_func("_getpty") or
       have_func("ioctl")